A facile electrochemical chiral sensor for tryptophan enantiomers based on multiwalled carbon nanotube/hydroxypropyl-β-cyclodextrin functionalized carboxymethyl cellulose

The development of facile and convenient sensors for the chiral recognition of enantiomers is of great significance for medical and life science. Herein, a sensitive electrochemical sensor for the chiral recognition of tryptophan (Trp) enantiomers was developed based on the assembly of cellulose grafted with hydroxypropyl-β-cyclodextrins (CMC-CD), multi-walled carbon nanotubes (MWCNTs) and copper ions on the surface of a GCE. The morphologies and electrochemical behaviors of the prepared electrode (GCE/MWCNTs/CMC-CD-Cu) were characterized by differential pulse voltammetry (DPV), FT-IR, XPS, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The oxidation peak current ratio (IL/ID) of DPV could be reached at 2.2 under the optimal experimental conditions. Compared with D-Trp, the higher electrochemical signal of L-Trp was ascribed to the stronger affinity for L-type tryptophan. Additionally, the as-prepared chiral sensor was successfully utilized to analyze the amount of D-Trp in the racemic mixture.